Abstract
The purpose of this study was to evaluate the effects of four anesthetic regimens on in vivo contractile function of mouse ankle dorsiflexor muscles. The torque-frequency and torque-velocity relationships were determined for the following anesthetics: fentanyl-droperidol and diazepam (F-d/d); ketamine and xylazine (K/x); pentobarbital sodium (Ps); and methoxyflurane (Mf). Mf, Ps, and F-d/d regimens resulted in comparable contractile responses at low doses, whereas K/x produced a relative depression in isometric contractile function as shown by a decrease in the torque-time integral at the 300-Hz stimulation frequency (-13.9%; P < 0.050. Moreover, K/x caused a shift to the left in the torque-frequency curve as indicated by increases in torque-time integrals at 25 and 50 Hz. Both Ps and F-d/d regimens exhibited dose- dependent effects during the isovelocity contractions. Ps significantly reduced work (-28.7%) and average power (-28.9%) at 800°/s at the high dose. In contrast, F-d/d anesthesia resulted in increases in peak torque (1620%) and work (15-18%) output at all eccentric contraction velocities at the high dose, whereas average power was increased only at 800 (17%) and -1,000°/s (17%). In conclusion, commonly used anesthetic regimens can affect the contractile response in vivo; K/x and Ps yield smaller torque outputs, whereas Mf and F-d/d consistently produce larger contractile responses. Mf and F-d/d are recommended for use in studying skeletal muscle function in mice in vivo.
Original language | English (US) |
---|---|
Pages (from-to) | 332-340 |
Number of pages | 9 |
Journal | Journal of applied physiology |
Volume | 80 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1996 |
Keywords
- average power
- concentric
- eccentric
- isometric
- peak torque
- work